OBJECTIVE: To determine the accuracy of intravenous contrast-enhanced computerized tomography (CECT) in the detection of potentially life-threatening retroperitoneal hemorrhage in patients sustaining pelvic fractures, acetabular fractures or both. DESIGN: Retrospective review of sequential patients identified over a 1-year period by using a prospectively collected trauma database at two Level I trauma centers. MATERIALS AND METHODS: A group of patients admitted to one of two Level I trauma centers with pelvic or acetabular injuries between September 1, 1995, and September 30, 1996, was identified by using a prospectively collected trauma database. From this cohort, we selected those individuals who had undergone intravenous CECT scanning within 24 hours after admission and who had an Abbreviated Injury Score more than 3 because of their pelvic injury. Those individuals who required arterial embolization for uncontrolled hemodynamic shock were categorized as having "significant arterial bleeding" attributable to their pelvic injury. Individuals who regained hemodynamic ,stability without embolization were categorized as having "no significant arterial bleeding." Two observers who were blinded to clinical information and the results of angiography reviewed all injury radiographs and computed tomographic scans. The presence or absence of contrast extravasation on intravenous CECT was recorded. Each case was then categorized into a 2 x 2 table depending on the presence of contrast extravasation on CECT and the need for arterial embolization to determine the accuracy of the "contrast extravasation sign." RESULTS: Of the 192 eligible patients, 111 met the inclusion criteria. Eleven patients required an angiogram for ongoing hemodynamic instability. The sensitivity of extravasation on contrast enhanced computed tomography representing a significant arterial bleeding was 80%, and the specificity was 98%. The predictive value of a positive contrast "extravasation sign" was 80%, whereas the predictive value of a negative test was 98%. The likelihood ratio of a positive test was 40.4, and the likelihood ratio of a negative test was 0.204. CONCLUSION: The finding of contrast extravasation on CECT is highly suggestive of significant arterial bleeding that requires early angiographic embolization to restore hemodynamic stability.